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A-LevelMathematicsProbability and statistics9709/63 · May/June 2022 · Q64 Marks

A random sample of 5 values of a variable X is given below. 2 3 3 5 a

(a)Find an expression, in terms of a, for the mean of these values.[1]
(b)Find and simplify a quadratic equation in terms of a and hence find the value of a.[3]

Mark scheme

Marking points from the official mark scheme (May/June 2022). The mark or mark type is shown in brackets.

[B1] (13+a)/5
[M1] (1/4) × (47 + a² - (13+a)²/5) = 4
[A1] 2a² - 13a - 7 = 0
[A1] a = 7

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About this question

Topic: Probability and statistics, A-Level Mathematics (syllabus 9709). Structured question, 4 marks.
Source: A-Level Mathematics, May/June 2022 Paper 6 Variant 3, question 6.

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